A trocar sleeve of this type is known from patent WO 2010/136805 A1, although the two sleeve parts are two telescope-type straight tubular pieces that can slide into and out of one another and whose relative sliding either follows a straight line or moves along a helical spiral. The radial outer sleeve part is connected on its proximal end with a head piece that comprises an insulation for gas-tight insertion of an instrument into the trocar sleeve and a fluid connection support, and the radially inner sleeve part has a flexible ring-shaped flange on its distal end.
A trocar sleeve is a medical instrument that is used in minimally invasive surgery for inserting instruments into the human or animal body. In a minimally invasive surgical procedure, a trocar, which consists of a trocar sleeve and a trocar mandrel that is enclosed in the trocar sleeve, is used, first, to provide access to a body cavity. For this purpose the tip of the trocar mandrel is applied on an incision on the skin and is then pushed through the epithelium. Then the trocar mandrel is withdrawn from the trocar sleeve; the trocar sleeve remains inserted in the body. Through the trocar sleeve it is then possible to insert, in alternation, instruments such as endoscopes, forceps, scissors, sewing instruments and the like into the body cavity to perform surgical procedures.
The flexible flange on the distal end of a trocar sleeve unfolds below the perforated epithelium and can then be secured with a corresponding additional flange from outside in order to ensure secure anchoring on the epithelium. To make it possible for the flange to unfold below the epithelium, the trocar sleeve must be slid relatively deeply into the body, and in addition a flexible flange made of rubber or the like must be relatively thick to allow it to be effectively secured from outside, so that the flange, even during an intervention, takes up relatively much space below the epithelium. In addition, most trocar sleeves are designed for a certain minimum thickness of the epithelium. For these reasons the known trocar sleeves are not suited for some operations, for instance operations on small children or on the thyroid.
The documents US 2008/0242930 A1, DE 10 2009 014 525 A1 and US 2002/0042606 A1 each disclose an instrument for providing access for surgical interventions, said access comprising two elements that can pivot around an axis running perpendicular to the instrument longitudinal axis and that can be unfolded below the epithelium to form a type of flange, likewise requiring relatively a great deal of space below the epithelium.